Pulse-wave recorder



May 20, 1924. 1,494,868

F. B. sANBoRN PULSE WAVE RECORDER Fi1 ed June 13 1923 14 46 14 *"Wrlr':

if TJ Patented May 20, 1924..

mit

stares :at ostias.

FRANK B. SANBQRN, 0F CAMBRIDGE, MASSACHUSETTS.

PULSE-WAVE RECORDER.

.Application filed June 13, 1923. Serial No. 645,173.

producing a record of the expansion and contraction of blood-vessels, as the veins and arteries, for clinical purposes. In this connection, very small actuating forces are dealt with, and they must overcome substantial resistances in the inertia of the transmitting and recording elements.` Objects of the invention are vto effectively receive the impulses from the blood-vessels, and to generally render the recording apparatus convenient and reliable in use. v

In the accompanying drawing, Fig. 1 illustrates, in perspective, one embodiment of my invention; Fig. 2 is an enlarged longitudinal, vertical, sectional detail lthrough the impulse-receiving chambers; Fig. 3 is a front elevation of one of said chambers, with partsbroken away; and Fig. 4 is a perspective view of such chamber.

Similar characters of reference are applied to like parts throughout the several Views of the drawing.

Near one extremity of a base-plate 10 is xed a standard 12 having, projecting at opposite sides of its upper end, brackets 1,4, 14 to' support impulse-receiving chambers 16, 16. These chambers act in exactly the same manner to respectively produce simulta neous tracings from different blood-vessels, as a vein vand an artery, and are organized in substantially the same manner. quently, but one will be described in detail. Considering, then, one section of this double receiving mechanism, its bracket 14 is slotted longitudinally at 17 to receive a ni ple 18, which is a part of an inlet-condult communicating with the chamber and continued from said chamber by a exible pipe 20. At the outer extremity of this pipe 1s connected any convenient form of transmitting device (not illustrated), as a chamber closed at one side by an elastic diaphragm, which, when applied to the b1ood-vessel from -which a record is to be produced, transmits to the receivingmechanism impulses in the air contained in the system, and set up by the ex pansions and contractions.- The nipple 18 55 enters an .inlet-opening of the chamber 16, this opening being formed in a plate 22 furnishing the outer wall of the chamber. The plate is clamped against the inner face of ythe bracket 14 by a nut '24 threaded upon 60 the nipple and contacting with the opposite or outer' side ofthe bracket to hold the chamber in place. The front wall of this receiving chamber consists of a diaphragm 26, of some such elasticmaterial as sheet rubber, secured Ato the periphery of the plate by a band 28. Surrounding the inlet-opening, preferably concentric with the circular perip ieryofthe plate 22, is a wall 30 projecting from the inner face of the plate to- Ward the diaphragm, which, as it is drawn about the plate by' the securing band, contacts rmly with said wall. The'height or outward extension of this wall, whichv is 'much'less than the distance between its op- 75 posite sides, is such as to furnish a relatively shallow space beneath the diaphragm, this j space constituting the receiving chamber. The cubic capacity of the space is small as compared with the air displaced at the transmitting device by the pulsation of the blood-vessel. Consequently, there are produced movements of the diaphragm of substantial extent.

phragm to the inleteopening through the plate 22 give effective impact of the air-impulses without dissipation of their energy.V Moreover, the plate furnishes a stop-surface with which the diaphragm promptly contacts if suction is applied to the pipe 20, so that rupture of the diaphragm is prevented. Between'the wall 30 and the periphery of the plate there ,is formed, beneath the diaphragm, an auxiliary chamber 32, normally separated from the main chamber 16. From this auxiliary chamber, through the plate 22, is a contracted opening 34. I f undue pressure Ahe applied `to the pipe 20, the diaphragm, expanding, will leave the outer exma the diaphragm from dangerous stresses.

This outer chamber and its opening are also effective in lesseningstrains upon the dlaphragm in the opposite direction, as under The shallowness of the chamber and'resultant proximity of the dia- 85 I the influence of suction.y In this case, the contact' between the wall 3() and the diaphragm .becomes imperfect, so that air is permitted to pass through the opening 34, the chamber 32 and between the diaphragm and wall, and balance atmospheric pressure against the outer face of the former. While the normally e'ective diaphragm-area is confined within the wall 30, the total area from the periphery of the plate 22 gives greater elasticity than would one of less extent and a higher degree of responsiveness to applied impulses, there being capacity to yield from the peripheral securing means. On the other hand, the normal flexing being only of that portion within the wall, the inertia lof the part moved is minimized. rllhen, too, because of the relief or compensating effect betweeny the main and auxiliary chambers, a thinner, lighter and more elas- -tic diaphragm may be used without danger of rupturing. This increases the sensitiveness of the apparatus.

Fixed to the center of the diaphragm, as by an adhesive, is a thin plate 36 having a contact-projection 38. Resting against the outer extremity of this projection or stud, which is flattened horizontally to be of some lateral extent substantially paralleltothe di: aphragm, is a'vertical contact member 40, of

' generally inverted U-form, fixed to the arm of a recording lever 42. Since it is desired that the levers of both receiving chambers shall be maintained against their studs by a force acting in thesame direction, thisbeing gravity, the engagement'between the contact members ,and studs is at the opposite sides of the fulcra of the levers. That is, the lever seen at the rightvof Fig. 1 has its contact membern 40 fixed to its long arm, while upon the associated'lever, the contact member is secured to a short arm at the opposite side of the fulcrum, this being as appears in Figs. 3 and 4. Referring particularly to Fig. .4, itwill be noted that the ends of the studs or projections 38 and the mem'- bers 40, which are in contact, are of relatively small transverse dimensions, and are extended longitudinally, crossing each other at an angle, so, that they give propery enl gagement during movement of the elements,

.and yet engage over so small an area as to m1n1m1ze fr1ct1on. These intersectmg edges1 of considerable longitudinal extent, also fa vcilitate the assembling of the apparatus, lessening the precision of workmanship required. The fulcrum of each of the recordimg levers 42 may be furnished by opposed conical pointed screws 44, a44. threaded lthrough anl arm 46 projecting from the bracket 14. Because ofthe relatively great extent of movement of the diaphragm upon the chamber 161of small cubic capacity, and

'under considerable force ofk the direct impact of impulses from the inlet-opening of Laeaeee the nipple 18 in'close-proximity to the dia-Y phragm, the ratio of the short arm of the lever, between the point of contact of t-he member 40 and the fulcrum, and the long arm of said lever, which, at its outer extremity, carries a Vrecording device, need not be very great, the increase in the length of the short arm providing' greater power to overcome inertia and resistance. Hinged at 48, upon the long arm of the lever 42, is a recording pen 50, which may be trough-shaped to contain a considerable' supply of ink. To hold the members 38 and 40 in operating contact, so that t-he pen may be caused to follow the fluctuations of the diaphragm, under the influence of the impressed impulses from the expanding and contracting blood-vessel, the force of gravity is utilized. This force is vmadeeflective by inclining the base 10 upon oneedge 52 by means vof a skeleton-leg 54, pivoted at' 56 beneath the base. The pivoting of the leg allows it to be brought into parallelism with the base, so that` the apparatus ymay be more conveniently packed for transportation. When thus inclined, the weight of the long arm of the lever forces this down against the contact member 40 of one chamber, and moves the Ashort arm 55 up against said member of the other chamber, their engagement in ,each case being constantly maintained. Such a connecting means, with capability for independent movement between the elements, is highly advantageous as compared with such a positive articulation as would be furnished by a link, since friction is to a great de-A gree eliminated, and there is no tendency for the engaging parts to bind and resist movement through errors in assembling or through distortion in use. Secured to the bracket 14 and extending on opposite sides of the lever 42 is an arm 57, which serves as a stop to guard the elements againstexcessive oscillation of the lever in either direction. Y i

. Adjacent to the edge 52 .of the base is attached a casing. 58, containing a clockwork or other motor mechanism to advance,l in

constant time relation, the surface upon which the pens areto record the received impulses. This surface is preferably furnished bya ribbon of paper 60, which is takprojecting horizontally'from the inner sideV of the casing. The former serves as a table,

over which'the pens act. The latter maintains the ribbon smoothly in contact with this table.

lVith the transmitting devices in placey studs 38 back and forth, acting through the.

contact members l0 upon levers 42 to carry the pens 50 transversely ot' the ribbon 60. Since the surface of this ribbon is advancing at a regular rate beneath the pens, there are inscribed upon it lines in wave form, which `record the action of, the blood-vessels under observation. At 72, a tracing made from an artery appears, and at 74 one from avein.

`Toturnish convenient means for determining the timing of the received wave, an additional pen 7 6 may act near the inner edge of the ribbon, this being actuated by clockwork to produce marks 7 8. These marks preferably indicate seconds, every fifth indication being omitted to make the time more readily readable. A knob 80, projecting through a slot in the casing, serves, by its movement, to start andv stop the motor mechanism for the ribbon,` while a similar knob 82 gives control over the `clockwork actuating the pen 76. A`hook 84 is fixed to the upper surface of the base at the edgeopposite the casing 58, this facilitating the handling of the apparatus. 1

rounding I claim f 1. A pulse-Wave-recording apparatus comprising an impulse-.receiving chamber hav- 'ing an inlet-opening, a contact-wall surrounding the opening, a` diaphragm stretched across the vvallto ormone side ofv the chamber, means spaced` from the wall for securing the diaphragm in place, and

recording mechanism under the influence f the diaphragm.

l 2. A pulse-wave-recording apparatus comprising an impulse-receiving chamber having an inlet-opening, a contact-wall surroundin v the opening, a diaphragm stretche across the wall to yform one side of the chamber, means spaced from the wall` for 'securing the diaphragm in place, there.

being an auxiliary chamber betweenuthe wall and securing means, and recording mechanism under the influence of the diaphragm.

3. A pulse-wave-recording apparatus comprising an vin ipulse-receiving chamber having an inlet-opening, a contact-wall surfthe opening, a diaphragm stretched across the wall to form. one side of .the chamber, means spaced from the wall for securing the diaphragm in place, there being an auxiliary chamber betweenthe wall and securing means from' which auxiliary chamber is an opening, and recording mechanism under the influence of the diaphragm.

4. A pulse-wave-recording apparatus comprising an impulse-receiving chamber havingv an inlet-opening, a contact-wall surrounding the opening, a diaphragm stretched across the wall to form one side of the chamber, the diaphragm being in close proximity to the inlet-opening, means for holding the diaphragm stretched across the wall, and recording mechanism actuated by the diaphragm. l y

. 5. A pulse-wave-recording apparatus comprising a plate through which is an opening, an inlet-tube lconnected to the opening, a wall surrounding the opening between it and the periphery of the plate, a diaphragm contacting With the outer extremity of the Wall andfwith the periphery of the plate, and recording mechanismv actuated by the diaphragm.

6. Apulse-wave-recording apparatus comprising a plate through which is an opening, an inlet-tube connected to the opening, a

`wall surrounding the opening between it and the periphery ofthe plate, there being an opening through the plate between its periphery and the wall, a diaphragm contacting with the outer extremity of the wall and with the periphery of the plate, and recording mechanism actuated by the diaphragm.

7 f A pulse-wave-recording apparatus comprising aV plate thgough which is an opening, an inlet-tube connected to theopening, a wall .surrounding the opening between it and the periphery ofV the plate, the-height of said wall being much less than the distance betweenc its opposite sides, -a diaphragm stretched across the outer extremity of the wall, and recording mechanism under the influence of the diaphragm.

8. A plilse-wa've-recording apparatus comprising an impulse-receiving diaphragm,

and a recording member arranged to be held by gravity. in co-operation with the diaphragm. l l

9. A pulse-wave-recording apparatus comprising an impulse-receiving diaphragm, a member carried thereby, and a recording lever having a portion normally. resting against the member but free to move inde-v pendently thereof.

1 0. A pulse wave recording ap aratus i comprising an impulse-receiving diapxhragm,

a member carried thereby, and a recording lever having a portion .normally resting against the member but free to move independently thereof, the contacting portions` being narrow and crossing each other at an angle.

' 11. AI pulse-wave-recording apparatus comprising. a chamber having a `movable wall, a projection froml the wall having a terminal portion extending substantially parallel to said `wall, and a recording lever normally maintained by gravity in Contact With such terminal portion of the projection.

12. A pulse Wave recording apparatus comprising a plate through which is an` opening, an inlet-tube connected to the opening, a flange surrounding the opening between it and the periphery of the plate, a diaphragm stretched across the flange, means for securing the diaphragm to the periphery of the plate, a stud projecting from the diaphragm between opposite portions of the flange, and a recording lever bearing against the extremity of the stud.

13. A pulse Wave recording apparatus comprising -a base, means for holding the f base in an -inclined position, and recording mechanism including elements maintained in operative relation by virtue of the inclination of theybase. c

14. A pulse-Wave-recording apparatus comprising a base, means for holding the base in an inclined position, an impulsereceiving chamber having a movable projection,'and a recording lever maintained in Contact with the projection by the inclination of the base.

15. A pulse Waverecording apparatus comprising a base, impulse-receiving mechanism carried by the base, recording mechanism mounted near one edge of the base, and a supporting leg pivoted near the opposite side ofthe base from the recording mechanism.

16. .A pulse wave recording apparatus comprising a base, impulse-receiving mechanism mounted thereon, a pen actuated by `said mechanism, supports for a. recordribbon, a casing carried by the base and containing motor mechanismy for the ribbon, and a guide for the ribbon extending from the side of the casing adjacent to the pen.

Signedn at Boston, in the county of Suffolk and State of Massachusetts, this fourth day of'June, 1923.

- FRANK B. SANBORN. 

